Background: The onset of a noncompound nuclear fission (NCNF) process such as quasifission was already predicted for heavy symmetric systems with the charge product greater than 1400. However, quasifission is observed indeed in very asymmetric reactions forming ${}^{216}\mathrm{Ra}$ with much lower charge product($\approx 700$). A comprehensive idea about the dependence of quasifission on entrance channel mass asymmetry with smaller charge product is still missing. A clear understanding is vital in the production of superheavy elements.

Purpose: To investigate limiting value of mass asymmetry near the Businaro-Gallone point where the fusion probability starts to deviate from unity.

Method: Evaporation residue (ER) cross sections were measured for ${}^{16,18}\mathrm{O}+{}^{181}\mathrm{Ta}$ reactions at $E_{\text{lab}}=68–110$ MeV using a recoil mass spectrometer and compared with coupled-channel and statistical model calculations.

Results: Below the Coulomb barrier region, coupled channel calculations reproduced the excitation functions of both ${}^{16,18}\mathrm{O}+{}^{181}\mathrm{Ta}$ reactions. Further, statistical model calculations with the same fission barrier scaling factor $k_f=0.95$ reproduced the experimental ER cross-section energies above the Coulomb barrier.

Conclusions: We do not observe any significant signature of fusion suppression in ER excitation functions of ${}^{18}\mathrm{O}+{}^{181}\mathrm{Ta}$ reaction, in comparison with that of ${}^{16}\mathrm{O}+{}^{181}\mathrm{Ta}$. This may be attributed to the high resemblance in mass asymmetry and other structural properties of these systems. A fission barrier scaling factor, $k_f=0.95$ used in the statistical model calculations for both systems, explains the experimental ER and fission cross sections, indicating the absence of any NCNF.

Kinetic equilibration of the matter and baryon densities attained in the central region of colliding Au+Au nuclei in the energy range of $\sqrt{s_{NN}}=3.3–39$ GeV are examined within the model of three-fluid dynamics. It is found that the kinetic equilibration is faster at higher collision energies: the equilibration time (in the center-of-mass frame of colliding nuclei) rises from $\approx 5$ fm/$c$ at $\sqrt{s_{NN}}=3.3$ GeV to $\approx 1$ fm/$c$ at 39 GeV. The chemical equilibration, and thus thermalization, takes longer. We argue that the presented time evolution of the net-baryon and energy densities in the central region is a necessary prerequisite of proper reproduction of bulk observables in midrapidity. We suggest that for informative comparison of predictions of different models it is useful to calculate an invariant four-volume ($V_4$), where the proper density of the equilibrated matter exceeds a certain value. The advantage of this four-volume is that it does not depend on specific choice of the three-volume in different studies and takes into account the lifetime of the high-density region, which also matters. The four-volume $V_4=100$ ${\mathrm{fm}}^4/c$ is chosen to compare the baryon densities attainable at different energies. It is found that the highest proper baryon density increases with the collision energy rise, from $n_B/n_0\approx 4$ at 3.3 GeV to $n_B/n_0\approx 30$ at 39 GeV. These highest densities are achieved in the central region of the colliding system.

We study surface effects of neutron ${}^{3}P_2$ superfluids in neutron stars. ${}^{3}P_2$ superfluids are in uniaxial nematic (UN), ${\mathrm{D}}_2$ biaxial nematic (BN), or ${\mathrm{D}}_4$ BN phase, depending on the strength of magnetic fields from small to large. We suppose a neutron ${}^{3}P_2$ superfluid in a ball with a spherical boundary. Adopting a suitable boundary condition for ${}^{3}P_2$ condensates, we solve the Ginzburg-Landau equation to find several surface properties for the neutron ${}^{3}P_2$ superfluid. First, the phase on the surface can be different from that of the bulk, and symmetry restoration or breaking occurs in general on the surface. Second, the distribution of the surface energy density has an anisotropy depending on the polar angle in the sphere, which may lead to the deformation of the geometrical shape of the surface. Third, the order parameter manifold induced on the surface, which is described by two-dimensional vector fields induced on the surface from the condensates, allows topological defects (vortices) on the surface, and there must exist such defects even in the ground state thanks to the Poincaré-Hopf theorem: although the numbers of the vortices and antivortices depend on the bulk phases, the difference between them is topologically invariant (the Euler number $\chi =2$) irrespective of the bulk phases. These vortices, which are not extended to the bulk, are called boojums in the context of liquid crystals and helium-3 superfluids. The surface properties of the neutron ${}^{3}P_2$ superfluid found in this paper may provide us useful information to study neutron stars.

A detailed study of the $\beta$-delayed neutron emission properties of ${}^{137,138}\mathrm{I}$ and ${}^{144,145}\mathrm{Cs}$ has been performed by confining ions in the Beta-decay Paul Trap. The daughter ions following $\beta$ decay emerge from the trapped-ion cloud with negligible scattering allowing reconstruction of the recoil-ion energy from the time of flight. From this information, the neutron-emission branching ratios and neutron-energy spectra were deduced. The results for the ${}^{137}\mathrm{I}$ and ${}^{144,145}\mathrm{Cs}$ decays are in agreement with previous results performed using direct neutron-detection techniques. In the case of ${}^{138}\mathrm{I}$, a branching ratio of 6.18(50)% is obtained, yielding a value consistent with the more recent results, which are a factor of two larger than measurements made prior to 1978.

We report on the measurement of lifetimes of excited states in the near-mid-shell nuclei ${}^{164,166}\mathrm{Dy}$ using the gamma-ray coincidence fast-timing method. The nuclei of interest were populated using reactions between an ${}^{18}\mathrm{O}$ beam and a gold-backed isotopically enriched ${}^{164}\mathrm{Dy}$ target of thickness $6.3\mathrm{mg}/{\mathrm{cm}}^2$ at primary beam energies of 71, 76, and 80 MeV from the IPN-Orsay laboratory, France. Excited states were populated in ${}^{164}\mathrm{Dy}$, ${}^{166}\mathrm{Dy}$, and ${}^{178,179}\mathrm{W}$ following Coulomb excitation, inelastic nuclear scattering, two-neutron transfer, and fusion-evaporation reaction channels respectively. Gamma rays from excited states were measured using the $\nu$-Ball high-purity germanium (HPGe)-${\mathrm{LaBr}}_3$ hybrid $\gamma$-ray spectrometer with the excited state lifetimes extracted using the fast-timing coincidence method using HPGe-gated ${\mathrm{LaBr}}_3\text{−}{\mathrm{LaBr}}_3$ triple coincident events. The lifetime of the first $I^{\pi }=2^{+}$ excited state in ${}^{166}\mathrm{Dy}$ was used to determine the transition quadrupole deformation of this neutron-rich nucleus for the first time. The experimental methodology was validated by showing consistency with previously determined excited state lifetimes in ${}^{164}\mathrm{Dy}$. The half-lives of the yrast $2^{+}$ states in ${}^{164}\mathrm{Dy}$ and ${}^{166}\mathrm{Dy}$ were 2.35(6) and 2.3(2) ns, respectively, corresponding to transition quadrupole moment values of $Q_0=7.58\left(9\right)$ and 7.5(4) $e\text{b}$, respectively. The lifetime of the yrast $2^{+}$ state in ${}^{166}\mathrm{Dy}$ is consistent with a quenching of nuclear quadrupole deformation at $\beta \approx 0.35$ as the $N=104$ mid-shell is approached.

Nucleosynthesis in the first generation of massive stars offers a unique setting to explore the creation of the first heavier nuclei in an environment free of impurities from earlier stellar generations. In later generations of massive stars, hydrogen burning occurs predominantly through the CNO cycles, but without the carbon, nitrogen, and oxygen to catalyze the reaction sequence, first stars would have to rely on the inefficient $pp$ chains for their energy production. Observations of second and third generation stars show pronounced abundances of carbon and oxygen isotopes, which suggests a rapid conversion of the primordial abundances to heavier elements. While the triple-alpha-process primarily facilitates this conversion, there are alternative reaction sequences, such as ${}^2\mathrm{H}(\alpha ,\gamma ){}^6\mathrm{Li}(\alpha ,\gamma ){}^{10}\mathrm{B}(\alpha ,n){}^{13}\mathrm{N}$, that may play a significant role. To study such alternate reaction pathways for production of carbon and heavier nuclei, a number of new measurements are needed. In this work, new measurements are reported for the ${}^{10}\mathrm{B}(\alpha ,n){}^{13}\mathrm{N}$ reaction, extending the cross section down to 575 keV incident $\alpha$-particle energy. The measurements were made using a state-of-the-art deuterated liquid scintillator and a spectrum unfolding technique. An $R$-matrix analysis was performed in order to facilitate a comparison of the underlying nuclear structure with the reaction measurements. An unexpected upturn is observed in the low-energy $S$ factor that indicates the presence of a new low-energy resonance. A revised reaction rate is determined that takes into account the present data as well as other previous measurements from the literature that were previously neglected.

The phase diagram of isospin-symmetric chemically equilibrated mixture of $\alpha$ particles and nucleons ($N$) is studied in the mean-field approximation. Skyrme-like parametrization is used for the mean-field potentials as functions of partial densities $n_{\alpha }$ and $n_N$. We find that there is a threshold value $a_{*}$ of the parameter $a_{N\alpha }$ which describes the attractive interaction between $\alpha$ particles and nucleons. At $a_{N\alpha }<a_{*}$ the ground state of nuclear matter at zero temperature consists only of interacting nucleons, whereas at $a_{N\alpha }>a_{*}$ the nuclear ground state includes also an admixture of $\alpha$'s. We demonstrate that the equation of state of such $\alpha \text{−}N$ system contains both the first-order liquid-gas phase transition and the Bose-Einstein condensation of $\alpha$ particles.

In this paper, we investigate the production of a true muonium state, which is an atom consisting of a ${\mu }^{+}{\mu }^{-}$ bound state, by $\gamma \gamma$ interactions in ultraperipheral PbPb collisions, considering an accurate treatment of the absorptive corrections and for the nuclear form factor. The rapidity distributions and cross sections are estimated considering the Relativistic Heavy Ion Collider, Large Hadron Collider, and Future Circular Collider energies. Our results indicate that the experimental analysis can be useful to observe the true muonium state.

We develop the dynamical core-corona initialization framework as a phenomenological description of the formation of quark gluon plasma (QGP) fluids in high-energy nuclear collisions. Using this framework, we investigate the fraction of the fluidized energy to the total energy and strange hadron yield ratios as functions of multiplicity, and we scrutinize the multiplicity scaling of hadron yield ratios recently reported by the ALICE Collaboration. Our results strongly indicate that the QGP fluids are partly formed even at the averaged multiplicity for nonsingle diffractive $p+p$ events.

Beta-delayed-neutron ($\beta n$) spectroscopy was performed using the Beta-decay Paul Trap and an array of radiation detectors. The $\beta n$ branching ratios and energy spectra for ${}^{135,136}\mathrm{Sb}$ and ${}^{140}\mathrm{I}$ were obtained by measuring the time of flight of recoil ions emerging from the trapped ion cloud. These nuclei are located at the edge of an isotopic region identified as having $\beta n$ branching ratios that impact the $r$-process abundance pattern around the $A\approx 130$ peak. For ${}^{135,136}\mathrm{Sb}$ and ${}^{140}\mathrm{I}, \beta n$ branching ratios of $14.6\left(13\right)\%, 17.6\left(29\right)\%$, and $7.6\left(28\right)\%$ were determined, respectively. The $\beta n$ energy spectra obtained for ${}^{135}\mathrm{Sb}$ and ${}^{140}\mathrm{I}$ are compared with results from direct neutron measurements, and the $\beta n$ energy spectrum for ${}^{136}\mathrm{Sb}$ has been measured for the first time.

We reconsider the problem of the hyperon puzzle and its suggested solution by quark deconfinement within the two-phase approach to hybrid compact stars with recently obtained hadronic and quark matter equations of state. For the hadronic phase we employ the hypernuclear equation of state from the lowest order constrained variational method and the quark matter phase is described by a sufficiently stiff equation of state based on a color superconducting nonlocal Nambu-Jona-Lasinio model with constant (model nlNJLA) and with density-dependent (model nlNJLB) parameters. We study the model dependence of the phase transition obtained by a Maxwell construction. Our study confirms that also with the present set of equations of state quark deconfinement presents a viable solution of the hyperon puzzle even for the new constraint on the lower limit of the maximum mass from PSR $\mathrm{J}0740+6620$. In this work we provide with model nlNJLB for the first time a hybrid star EoS with an intermediate hypernuclear matter phase between the nuclear and color superconducting quark matter phases, for which the maximum mass of the compact star reaches $2.2M_{\odot }$, in accordance with most recent constraints. In model nlNJLA such a phase cannot be realized because the phase transition onset is at low densities, before the hyperon threshold density is passed. We discuss possible consequences of the hybrid equation of state for the deconfinement phase transition in symmetric matter as it will be probed in future heavy-ion collisions at the GSI Facility for Antiproton and Ion Research, the Nuclotron-based Ion Collider fAcility, and corresponding energy scan programs at the CERN Large Hadron Collider and the BNL Relativistic Heavy Ion Collider.

The low-energy excitations and $\beta$ decays of odd-$A$ nuclei are studied within the interacting boson-fermion model (IBFM), based on the Gogny-D1M nuclear energy density functional (EDF). The constrained Hartree-Fock-Bogoliubov (HFB) approximation is employed to compute potential energy surfaces in terms of triaxial quadrupole degrees of freedom for even-even Xe and Ba nuclei in the mass $A\approx 130$ region. The mean field approximation also provides spherical single-particle energies and occupation probabilities for the neighboring odd-$A$ nuclei. Those quantities represent a microscopic input for spectroscopic calculations in odd-$A$ Xe, Ba, Cs and La isotopes. The Gamow-Teller (GT) and Fermi (F) transition matrix elements needed to compute $\beta$-decay $logft$ values are obtained without any phenomenological fitting. It is shown that both the low-lying states and $\beta$ decays of the studied odd-$A$ systems are described reasonably well within the employed theoretical framework.

We posit a unified hydrodynamic and microscopic description of the quark-gluon plasma (QGP) produced in ultrarelativistic $p\text{−}\mathrm{Pb}$ and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$ and evaluate our assertion using Bayesian inference. Specifically, we model the dynamics of both collision systems using initial conditions with parametric nucleon substructure, a preequilibrium free streaming stage, event-by-event viscous hydrodynamics, and a microscopic hadronic afterburner. Free parameters of the model, which describe the initial state and QGP medium are then simultaneously calibrated to fit charged-particle yields, mean $p_T$, and flow cumulants. We argue that the global agreement of the calibrated model with the experimental data strongly supports the existence of hydrodynamic flow in small collision systems at ultrarelativistic energies, and that the flow produced develops at length scales smaller than a single proton. Posterior estimates for the model's input parameters are obtained, and new insights into the temperature dependence of the QGP transport coefficients and event-by-event structure of the proton are discussed.

Time-reversal violation (TRV) interactions between quarks which appear in the standard model (SM) and beyond-SM theories can induce TRV components in the nucleon-nucleon potential. The effects of these components can be studied by measuring the electric dipole moment (EDM) of light nuclei. In this work we present a complete derivation of the TRV nucleon-nucleon and three-nucleon potential up to next-to-next-to leading order (N2LO) in a chiral effective field theory $\left(\chi \mathrm{EFT}\right)$ framework. The TRV interaction is then used to evaluate the EDM of ${}^2\mathrm{H},{}^3\mathrm{H}$, and ${}^3\mathrm{He}$ focusing in particular on the effects of the TRV three-body force and on the calculation of the theoretical errors. In this work we limit our analysis to study the TRV potential contributions to the EDM without including TRV exchange currents, which we plan to add in a future work. Once added these exchange currents, in case of measurements of the EDMs of these nuclei, our results would contribute to the determination of the values of the low energy constants and to the identification of the source of TRV.

Background: Cross section data of neutron-induced spallation are requisite in order to study the transmutation of the long-lived fission products from the spallation. However, those data are very scarce at present due to the difficulty of providing a neutron source in the GeV region and the impossibility of the inverse dynamics.

Purpose: The present work is an attempt to probe the dynamic process of deuteron breakup in deuteron-induced spallation and discuss the possibility of measuring indirectly the cross section in neutron-induced spallation.

Method: The isospin-dependent quantum molecular dynamics model is applied to simulate the spallation process until the excitation energy of the hot fragment is less than 2 MeV/nucleon. The statistical model gemini based on the Hauser-Feshbach formalism is used to describe the deexcitation of the hot fragments.

Results: By comparing the calculations to the data, the theoretical framework is proved to be reasonable when predicting the neutron production in spallation. By investigating the deuteron breakup, deuteron-induced spallation is divided into deuteron absorbing, neutron stripping, proton stripping, and elastic breakup. It is found that the proton stripping plays the dominant role in the production of high-energy neutrons, while the neutron stripping is responsible for the emission of high-energy protons. Due to the weak binding of the deuteron, it is suggested that the combination of neutron stripping and elastic breakup in deuteron-induced spallation is equivalent to neutron-induced spallation.

Conclusions: Using the proton recoiling from the deuteron as the trigger signal, deuteron-induced spallation may be applied to measure indirectly the cross section in neutron-induced spallation.

We investigate an implication of the most recent observation of a second $J^{\pi }=2^{+}$ state in ${}^{12}\mathrm{C}$, which was measured using the ${}^{12}\mathrm{C}(\gamma ,\alpha ){}^8\mathrm{Be}_{(\mathrm{g}.\mathrm{s}.)}$ reaction. In addition to the dissociation of ${}^{12}\mathrm{C}$ to an $\alpha$-particle and ${}^8\mathrm{Be}$ in its ground state, a small fraction of events (2%) were identified as direct decays and decays to excited states in ${}^8\mathrm{Be}$. This allowed a limit on the direct $3\alpha$ partial decay width to be determined as ${\mathrm{\Gamma }}_{3\alpha }<32\left(4\right)$ keV. Since this $2^{+}$ state is predicted by all theoretical models to be a collective excitation of the Hoyle state, the $3\alpha$ partial width of the Hoyle state is calculable from the ratio of $3\alpha$ decay penetrabilities of the Hoyle and $2^{+}$ states. This was calculated by using the semiclassical Wenzel-Kramers-Brillouin approach and we deduce a stringent upper limit for the direct decay branching ratio of the Hoyle state of $\frac{{\mathrm{\Gamma }}_{3\alpha }}{\mathrm{\Gamma }}<5.7\times {10}^{-6}$, over an order of magnitude lower than previously reported. This result places the direct measurement of this rare decay mode beyond current experimental capabilities.

The effects of shape coexistence in ${}^{96}\mathrm{Y}$ and ${}^{96}\mathrm{Zr}$ on the ${\beta }^{-}$ first-forbidden decay of the $0^{-}$ ground state and Gamow-Teller decay of the $8^{+}$ isomer of ${}^{96}\mathrm{Y}$ to ${}^{96}\mathrm{Zr}$ were studied within the beyond-mean-field complex excited Vampir model. The structure of the parent and daughter states and the $\beta$-decay properties have been investigated using an effective interaction derived from a $G$ matrix based on the charge-dependent Bonn CD potential and a large model space. The influence of shape coexistence and mixing on the properties of the states involved in the investigated allowed and first-forbidden ${\beta }^{-}$ decays is discussed and comparison to the available data is presented.

It is shown that the Cholesky decomposition method, implemented in mirror nuclei to extract an orthonormal basis from a redundant set of states composed of a valence particle (hole) coupled to Tamm-Dancoff approximation (TDA) phonons, yields a few levels which violate the mirror symmetry, at variance with the shell model. A more appropriate implementation of the method is suggested which eliminates this inconsistency.

An experiment involving a heavy-ion-induced fusion-evaporation reaction was carried out where high-spin states of ${}^{123}\mathrm{Xe}$ were populated in the ${}^{80}\mathrm{Se}({}^{48}\mathrm{Ca},5n){}^{123}\mathrm{Xe}$ reaction at 207 MeV beam energy. Gamma-ray coincidence events were recorded with the Gammasphere Ge detector array. The previously known level scheme was confirmed and enhanced with the addition of five new band structures and several interband transitions. Cranked Nilsson-Strutinsky (CNS) calculations were performed and compared with the experimental results in order to assign configurations to the bands.

Background: The ${}^{29}\mathrm{F}$ system is located at the lower-$N$ boundary of the “island of inversion” and is an exotic, weakly bound system. Little is known about this system beyond its two-neutron separation energy ($S_{2n}$) with large uncertainties. A similar situation is found for the low-lying spectrum of its unbound binary subsystem ${}^{28}\mathrm{F}$.

Purpose: We investigate the configuration mixing, matter radius, and neutron-neutron correlations in the ground-state of ${}^{29}\mathrm{F}$ within a three-body model, exploring the possibility of ${}^{29}\mathrm{F}$ to be a two-neutron halo nucleus.

Method: The ${}^{29}\mathrm{F}$ ground-state wave function is built within the hyperspherical formalism by using an analytical transformed harmonic oscillator basis. The Gogny-Pires-Tourreil (GPT) $nn$ interaction with central, spin-orbit, and tensor terms is employed in the present calculations, together with different $\text{core}+n$ potentials constrained by the available experimental information on ${}^{28}\mathrm{F}$.

Results: The ${}^{29}\mathrm{F}$ ground-state configuration mixing and its matter radius are computed for different choices of the ${}^{28}\mathrm{F}$ structure and $S_{2n}$ value. The admixture of $d$ waves with $pf$ components is found to play an important role, favoring the dominance of dineutron configurations in the wave function. Our computed radii show a mild sensitivity to the ${}^{27}\mathrm{F}+n$ potential and $S_{2n}$ values. The relative increase of the matter radius with respect to the ${}^{27}\mathrm{F}$ core lies in the range 0.1–0.4 fm depending upon these choices.

Conclusions: Our three-body results for ${}^{29}\mathrm{F}$ indicate the presence of a moderate halo structure in its ground state, which is enhanced by larger intruder components. This finding calls for an experimental confirmation.